Auditory training programs are being used in many clinical settings as a remediation tool for people with various types of communication disorders. These training paradigms are often designed to improve the perception of certain types of acoustic information by using specific stimuli (or modifications thereof) and specific tasks. As an example, stimuli differing in voice-onset-time (VOT) are used to train the perception of VOT. Because physiological changes have been shown to coincide with improved perception of the trained stimuli, it is assumed that training alters the physiological detection of that specific cue. But, inherent in any training program is the fact that individuals experience repeated stimulus exposure, and they participate in perceptual baseline tasks where they must attend to the stimuli and execute a specific task. To date little is known about if or how repeated stimulus exposure and focused listening tasks (in the absence of training) modulate evoked brain activity, and it is important to understand the contribution of these variables before we can fully understand the physiological effects of training on the central auditory system (CAS). Therefore, the goal of this research program is to determine the effects of stimulus exposure and focused listening tasks on the brain. Because the P1-N1-P2 auditory evoked potential (AEP) has been used to examine the effects of speech and music training on the CAS, we examine the contributions of stimulus exposure, focused listening tasks, and training using this measure. To do this, three groups of young-normal hearing subjects will be tested. Group one will be the exposure group, where individuals only hear repeated stimulus presentations. Group two will participate in a perceptual task (without feedback) in addition to being exposed to the stimuli. Group three will participate in stimulus exposure, plus task, as well as training. Members of each group will be tested at the same points in time (two baseline measures, post -training, and one retention test). Using within and across group comparisons, the aims are to: 1) Examine the effect of repeated stimulus exposure on the brain using AEPs recorded from Group 1, 2) Examine the effect of repeated stimulus exposure in addition to a focused listening task on the brain using AEPs recorded from Group 2, 3) Examine the effects of exposure, tasks, and auditory training on the brain using AEPs recorded from Group 3, 4) Characterize between group differences using descriptive brain measures and look at individual differences within each population.